Because the TFT LCD generates very little radiation, and it is compact as well as power saving, accompanied with the progress in manufacturing TFT, the liquid crystal display (LCD) display panel is widely used in electronic products such as calculator, personal digital assistance, watch, lap top computer, digital camera, cellular phone, video product (e.g., monitor and television set) and the like. In addition, the manufacturer's investment has been placed in researching and developing equipment supporting the LCD display panel of bigger dimension, thus makes its' cost down, and stimulate its' need in market.
As to production, it takes a lot of time to find defects (defective cells) in a TFT panel, for example, when performing an analysis to a sample from a production line of TFT panel, such as an electricity test, the electricity of each of the gate-lines and signal-lines of a TFT panel must be obtained. Then judge from the reading of each of the electricity of each of the gate-lines and signal-lines, if anything abnormal is found, the number of the relative gate-line and signal-line will be marked and recorded. Thus the intersection of the marked gate-line and signal-line is marked as defective, and the number of gate-line, e.g. G100, and number of signal-line, e.g. S100, will be recorded, such as (G100, S100). Perform the process until all the defectives of the TFT are located, such as (G100, S100), (G100, S200) and (G200, S300), then use laser marker to mark around the defective TFT cell. After the defective TFTs had been located, the subsequent analysis using Scanner Electron Microscopy (SEM) or Focused Ion Beam (FIB) can be performed to inspect the marked defective TFTs.
Manually locating the defective TFTs are performed by an operator, who reads the number of gate-line and signal-line of responding defective TFTs, such as (G100, S100), (G100, S200) and (G200, S300), and then mark the defective TFTs one by one with a laser marker under the microscope. It takes a lot of time to find each of the defective TFTs, e.g., from around 30 minutes to 3 hours, it depends on whether the location of the defective TFT is at the center or at the edge of the TFT plate. Furthermore, no one can guarantee 100% accuracy in the forgoing operation, especially when it is a manual operation.
Accordingly, when performing sample analysis to a TFT LCD display panel, in order to save the time for finding and locating a defective TFT cell, and to increases its' accuracy, it is essential to develop a method and apparatus to improve locating the defective TFTs.